MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

Hi mon2,

I noticed on the board a bridged joint and I fixed it. Now machine fan is staying on but no display or chime.

Can you help?

[mon2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

What is the voltage of PP3V42_G3H ?

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

Showing as 3.48V

[mon2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

Good voltage.

Voltage of PPBUS_G3H ?

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

12.56v

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

Hi mon2, is it still BIOS chip?

[mon2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

My guess is yes. That should be the next phase of this repair. The ppbus_g3h voltage is good and confirms that the SMC IC has communicated with the local regulator to create this exact voltage value. Perhaps others can comment. Bios is not my area, yet.

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

Okay I will replace BIOS chip.

I removed RAM and I do not get any beeps, I am not sure if this is confirming of BIOS chip or not?

[mon2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

You missed an update from earlier...

What is the voltage on this ALL_SYS_PWRGD ?

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

@mon2 showing 3.28V

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

Is there anything significant about not having any beeps when no RAM is inserted? Or is this also indicating BIOS issue?

[mon2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

interesting,

https://logi.wiki/index.php/820-3115_Common_Issues

Is your logic board pulsing still every 5 seconds or no longer ?

What is the voltage of PPVCORE_S0_CPU_REG ?

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

No fans just stay on now

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

No beeps to indicate no RAM installed

[mon2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

What is the voltage of PPVCORE_S0_CPU_REG ?

[ugamazing]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

You need to inspect the entire board for more damage. If you found 2 bridges pads...then I'll bet anything there's either more damage (missing components, etc), or the board has been worked on before.

By the way, which 2 pads were bridged? Might be relevant.

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

You need to inspect the entire board for more damage. If you found 2 bridges pads...then I'll bet anything there's either more damage (missing components, etc), or the board has been worked on before.

By the way, which 2 pads were bridged? Might be relevant.

I am not sure exactly but I cleaned all around this area and used my solder wick to remove the bridge.

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

I managed to get it under the microscope.

[Gigabit2]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

[ugamazing]

Re: MacBook Pro Mid 2012 turns on, fans spin for five seconds and turns off, repeats

That area looks pretty rough, not going to lie.

What's going on in the top-right corner of the last picture? Is that a bridged cap with a loose resistor?? And that ripped-up trace in center-right of photo, make sure it's not creased/broken. Make sure none of those missing test-pads are actually through-board traces; hard to tell if a few spots are solder or missing pads, but I could definitely see that area being a problem...and maybe even other areas of the board if that one looks that rough. What's the reverse side of board look like in that same spot? I think that's a PGOOD enable IC in top-right as well, and it looks a little suspect.